We propose to continue the research and development within the Center for Bioelectric Field Simulation, Modeling, and Visualization, which officially began operations in September, 1999. In the intervening two years, we have developed a foundation in infrastructure, personnel, and the software engineering of their integrated problem solving environment, BioPSE. In this time, we have achieved many of the milestones proposed in the initial application: we have released several versions of both BioPSE and map3D to the scientific community; we have carried out development in all areas of the grant and published widely on the topics of original research; we have hosted a highly successful meeting of the Resource External Advisory board; and working closely with a subset of the Resource collaborators, we have shown the feasibility and utility of their approach to integrated software design and implementation. We are well poised to continue the Resource and have strong endorsements from their External Advisory Board, the collaborators who have benefitted from the Resource, and the University of Utah through its strong matching contributions. The broad application of the Resource remains bioelectric field research with special interest in cardiac and neurological electrophysiology. The recent growth in computational capabilities has made it feasible to begin to simulate the complexity of bioelectric sources and fields. We propose that the most efficient means of making optimal use of these computational resources is through a highly integrated, modular, extensible and portable open standard. We have created such a system in our Bioelectric Problem Solving Environment (BioPSE) and made available as open source code. The organization of the proposal reflects that of the Resource itself with four components dealing with each of BioPSE, modeling, simulation, and visualization. There are development and original research goals in each component t